The remit of this site is not discussion of the motivation of writers but the meaning of their words. We leave the reader to speculate on their motivation.

1. ”Something can happen” means that it is possible according to the laws of physics (or in our experience of the world).

2. ”Something may happen” means that it is possible according to the laws of society (or a social institution).

[See e.g. Merriam-Webster]

So I would interpret this as a combination of (1) a warning, and (2) a “legal” statement:

1. If you do this it is possible that your exam will be returned with a lower grade.
2. If the marker does lower your grade his action will be perfectly legitimate within our regulations.

The remit of this site is not discussion of the motivation of writers but the meaning of their words. We leave the reader to speculate on their motivation.

As a simplification, and in the context of the question, one can differentiate between “can” and “may” as follows:

1. “Something can happen” means that it is possible according to the laws of physics (or in our experience of the world).

2. “Something may happen” means that it is possible according to the laws of society (or a social institution).

[See e.g. Merriam-Webster]

So I would interpret this as a combination of (1) a warning, and (2) a “legal” statement:

1. If you do this it is possible that your exam will be returned with a lower grade.
2. If the marker does lower your grade his action will be perfectly legitimate within our regulations.

The remit of this site is not discuss of the motivation of writers but the meaning of their words. We leave the reader to speculate on their motivation.

1. ”Something can happen” means that it is possible according to the laws of physics (or in our experience of the world).

2. ”Something may happen” means that it is possible according to the laws of society (or a social institution).

[See e.g. Merriam-Webster]

So I would interpret this as a combination of (1) a warning, and (2) a “legal” statement:

1. If you do this it is possible that your exam will be returned with a lower grade.
2. If the marker does lower your grade his action will be perfectly legitimate within our regulations.

The remit of this site is not discussion of the motivation of writers but the meaning of their words. We leave the reader to speculate on their motivation.

1. ”Something can happen” means that it is possible according to the laws of physics (or in our experience of the world).

2. ”Something may happen” means that it is possible according to the laws of society (or a social institution).

[See e.g. Merriam-Webster]

So I would interpret this as a combination of (1) a warning, and (2) a “legal” statement:

1. If you do this it is possible that your exam will be returned with a lower grade.
2. If the marker does lower your grade his action will be perfectly legitimate within our regulations.